IOTA/ISUOG 2026: Terms and Measurements for Adnexal Masses
Why the Updated IOTA/ISUOG 2026 Lexicon is Needed
The updated IOTA/ISUOG 2026 consensus is not a new prognostic model but a standard for terms, definitions, and measurements for ultrasound descriptions of adnexal masses. Its goal is for ultrasound physicians, gynecologists, oncogynecologists, and researchers to have a uniform understanding of terms like 'unilocular', 'solid component', 'papillary projection', 'ascites', and 'color score'.
The practical purpose of the update is to reduce variability in protocols. Instead of vague phrases like 'complex cyst', 'suspicious inclusion', or 'rich vascularization', it is recommended to describe specific features: structure, contour, internal content, presence of septa, solid tissue, papillary projections, acoustic shadows, free fluid, and blood flow.
What to Consider as the Object of Description
The term 'adnexal tumor' in the consensus is used broadly: it refers to a mass in the adnexal area, regardless of whether it appears ovarian, tubal, paraovarian, or of unclear origin. It is important to separate two questions in the protocol: the morphology of the mass and the presumed organ source.
If normal ovarian tissue is visualized separately or peripherally to the mass, this should be noted. If the origin is unclear, it is more accurate to write 'adnexal mass of unclear organ affiliation' rather than artificially attributing it to the ovary.
Basic Morphological Categories
Description begins with the overall architecture. A unilocular mass contains one cystic cavity and has no solid components. A multilocular mass contains more than one locule, separated by septa. A solid mass is predominantly composed of tissue rather than fluid. A multilocular-solid mass combines several cystic locules and a solid component.
These categories do not replace risk assessment. They are needed as the first layer of the protocol, after which walls, septa, papillary projections, internal content, shadows, blood flow, and free fluid are sequentially described.
Key Measurements: What Must Be Recorded
The mass is measured in three mutually perpendicular dimensions. The maximum dimension is usually listed first in the report, followed by the two orthogonal dimensions. The measurement should encompass the entire mass, including cystic and solid parts, septa, and outer contours.
The solid component is described separately. If there are several solid areas, the largest is measured. Papillary projections should not be 'dissolved' in the general description of the wall: they need to be counted, measured, and their location specified—whether from the wall or septum.
For dynamic observation, it is important to maintain the same methodology: the same access, a close planar slice, and the same understanding of the outer contour. Comparison based on a single diameter is less reliable than comparing three dimensions and morphology.
Threshold Definitions and IOTA/ISUOG Classes
| Feature | Definition or Class | How to Write in the Protocol |
|---|---|---|
| Mass Size | Three mutually perpendicular measurements | For example: 'adnexal mass 62 × 48 × 41 mm' |
| Unilocular Structure | One cystic cavity | 'Unilocular cystic mass' |
| Multilocular Structure | More than one locule, separated by septa | 'Multilocular cystic mass' |
| Papillary Projection | Solid protrusion into a cystic cavity with a height of ≥3 mm | Specify number, maximum height/size, and base: wall or septum |
| Color score 1 | No blood flow detected | 'Color score 1' |
| Color score 2 | Minimal blood flow | 'Color score 2' |
| Color score 3 | Moderate blood flow | 'Color score 3' |
| Color score 4 | Very marked blood flow | 'Color score 4' |
Papillary Projections: A Common Area of Error
The main numerical boundary is a height of ≥3 mm. A small irregularity of the wall with a lesser height should not automatically be called a papillary projection. The measurement is performed from the surface of the wall or septum to the apex of the protrusion into the cystic cavity.
In the protocol, it is useful to indicate: the number of projections, the size of the largest, the surface of the base, the presence of blood flow inside, and any associated solid component. The phrase 'papillary growths?' without measurement and Doppler assessment reduces the reproducibility of the description.
Septa, Walls, and Solid Component
A septum is a partition dividing cystic locules. It is necessary to describe not only the fact of septa but also their character: smooth or irregular, thin or thickened, with or without blood flow. If a papillary projection is attached to a septum, this is noted separately.
A solid component is considered a tissue area distinguishable from the fluid content. Blood flow helps confirm the tissue nature, but the absence of a Doppler signal does not exclude a solid component. Acoustic shadows are also described separately, as they are an independent ultrasound feature.
Content of the Cystic Part
Cystic content is recommended to be described in a standardized manner: anechoic, low echogenicity, 'ground-glass', hemorrhagic, mixed. Important are homogeneity, the presence of suspension, clots, levels, echogenic inclusions, and the mobility of the content when the probe position is changed.
The term 'complex cyst' is better not used as a final diagnosis: it encompasses too many different situations. Instead, specific components should be listed: number of locules, type of content, septa, solid areas, papillary projections, and blood flow.
Doppler: Why a Color Score is Needed Instead of Epithets
IOTA/ISUOG maintains a four-point semi-quantitative assessment of blood flow. Color score 1 means no visible blood flow, 2 means minimal, 3 means moderate, and 4 means very marked. The scale applies to the mass as a whole and should be assessed after optimizing Doppler settings.
In the protocol, it can be additionally specified where the blood flow is located: in the wall, septa, papillary projection, or solid component. But the final category should remain in the format of color score 1–4 to ensure the description is comparable with IOTA approaches.
Free Fluid and Extra-Ovarian Signs
Free fluid is described by location. For IOTA, the term 'ascites' is important as fluid outside the Douglas pouch; isolated small fluid in the posterior cul-de-sac should not automatically be called ascites. It is better to directly state in the protocol: 'free fluid only in the Douglas pouch' or 'fluid extends beyond the pelvis'.
Signs of extra-ovarian spread, if visible, are also recorded: peritoneal nodules, omental changes, hydrosalpinx, bilaterality, relation to the uterus and ovary. These signs do not replace the morphological description of the mass itself.
Minimum Protocol Template
- Location: right, left, bilateral; presumed origin—ovarian, extra-ovarian, or unclear.
- Size: three mutually perpendicular diameters of the entire mass.
- Architecture: unilocular, multilocular, solid, multilocular-solid.
- Cystic content: type of echogenicity and homogeneity.
- Walls and septa: smooth or irregular, presence of thickening.
- Solid component: presence, maximum size, location.
- Papillary projections: number, size, base; remember threshold ≥3 mm.
- Doppler: color score 1–4 and location of blood flow.
- Free fluid: only Douglas pouch or beyond.
- Comparison with previous studies: sizes and morphological changes.
This template makes the conclusion compatible with the IOTA/ISUOG 2026 consensus and suitable for further risk stratification, routing, and dynamic observation.
Frequently asked questions
How does the IOTA/ISUOG 2026 consensus differ from a risk model?
It standardizes terms, definitions, and measurements. The lexicon itself does not provide a probability of malignancy but ensures correct input data for IOTA approaches and clinical decision-making.
When should a wall irregularity be called a papillary projection?
Only if it is a solid protrusion into a cystic cavity with a height of ≥3 mm. Smaller irregularities should be described as wall irregularities, not substituting the term.
Should 'complex cyst' be written in the conclusion?
It is better to avoid this term as a final description. Specific morphology should be indicated: number of locules, content, septa, solid component, papillary projections, color score, and free fluid.